1. Field of the Invention
The present invention relates to a card and a process for producing the card. More particularly, the present invention relates to a card which is sealed by using a composition of the ionizing radiation curing type, shows excellent adhesion between a substrate sheet on which an IC chip and other members are disposed and a cover sheet and has faces with little unevenness and suitable flexibility and a process for producing a card such as IC cards having the above characteristics and excellent reliability with excellent productivity.
2. Description of Related Art
IC cards are generally produced by integrally laminating a cover sheet to a substrate sheet on which an IC chip and members related to the IC chip such as an antenna, chip condensers, batteries and electronic circuits are disposed, followed by forming prints for showing various informations, magnetic stripes and embosses on the face of the cover sheet. As the process for laminating the substrate sheet and the cover sheet, in general, a process of heat sealing and a process using an adhesive are used.
However, the process of heat sealing has drawbacks in that the process cannot be used when the electronic members disposed on the substrate sheet do not allow the temperature and the pressure of working necessary for the process and that specific types of the substrate sheet and the cover sheet must be used. When an adhesive is used for the heat sealing, the adhesive is restricted similarly depending on the type of electronic members disposed on the substrate sheet and some of conventional adhesives of the hot melt type cannot be used. Cards obtained by lamination using an adhesive of the hot melt type have a drawback in that the adhesive strength is small and the substrate sheet and the cover sheet tend to be separated. Therefore, special expensive adhesives must be used as the sealing material for cards in the process of heat sealing.
A card which shows excellent adhesion between a substrate sheet and a cover sheet and has faces with little unevenness caused by the IC chip and members related to the IC which are disposed inside, suitable flexibility and excellent reliability is required as the IC card.
An object of the present invention is to provide a card sealed by using a sealing composition which gives excellent adhesion between a substrate sheet on which an electronic chip and members related to the chip are disposed and a cover sheet and has faces with little unevenness, suitable flexibility and excellent reliability and a process for producing a card having the above characteristics with excellent productivity.
As the result of intensive studies by the present inventors to achieve the above object, it was found that a sealing composition which comprises specific components and can be cured by irradiation of an ionizing radiation is suitable for achieving the object and that, when the sealing composition is disposed between a substrate sheet and a cover sheet and cured by irradiation of an ionizing radiation, a card which shows excellent adhesion between the substrate sheet and the cover sheet and has faces with little unevenness, suitable flexibility and excellent reliability can be obtained with excellent productivity. The present invention has been completed based on this knowledge.
The present invention provides:
(1) A card sealed by using a composition which comprises (A) an acrylate compound polymerizable by an ionizing radiation and (B) 1 to 40 parts by weight of a polyfunctional isocyanate compound per 100 parts by weight of said acrylate compound and can be cured by irradiation of the ionizing radiation; and
(2) A process for producing a card which comprises disposing a coating layer of a composition for sealing a card described in (1) on a face of a substrate sheet on which an electronic chip and members related to the electronic chip are disposed, the electronic chip and the members being disposed at least on one of the faces of the substrate sheet, tightly placing a cover sheet on the coating layer and curing the composition by irradiating an ionizing radiation to the coating layer.